Figures shared with the Guardian by Generation Rent suggest landlords could be gaining as much as £26.7bn a year from the taxpayer. Photograph: Christopher Thomond/Guardian

Private landlords are benefiting from subsidies worth the equivalent of £1,000 for every household in the UK, the campaign group Generation Rent has claimed, with tax breaks and housing benefit bolstering their gains from house price increases.

Figures shared with the Guardian by the group suggest landlords could be gaining as much as £26.7bn a year from the taxpayer, equal to £1,011 each for the country’s 26.4m households.

The buy-to-let industry has boomed in recent years as the rising rents and house prices have made property an increasingly attractive investment for those with enough money to raise a deposit.

On Saturday, the letting agents ludlowthompson said data from HM Revenue & Customs showed the total number of buy-to-let investors in the UK had increased by 120,000 in 2014, to 1.6 million. New pension freedoms set to come into force in April are expected to lead to even more landlords entering the market.

Mortgage lenders have reduced rates on buy-to-let loans and made it easier for landlords to raise funds, as they try to build market share. These mortgages are not covered by the strict new lending rules introduced in April last year, which mean would-be homebuyers have to show they can afford interest payments even if rates rise.

The group’s figure is made up of £9.3bn of housing benefit paid on behalf of low-income tenants, £1.69bn through the “wear-and-tear” tax relief landlords can claim on their properties, £6.63bn of tax that landlords do not have to pay on mortgage interest payments and £9.06bn of tax landlords do not pay on their annual average capital gains.

Generation Rent calculated that landlords, who house 4.75m households in the UK, are earning £77.7bn a year: £42.3bn in rent and £35.4bn in rising house prices. Through income tax on rent and capital gains tax on sold properties, it estimated they were handing £8.9bn to the taxman.

The campaign is calling for an additional landlord levy of 22% on rental income, which it said would recoup the £9.3bn housing benefit bill and should be used to fund 90,000 new council houses.

Alex Hilton of Generation Rent said: “While renters have borne the brunt of austerity, landlords have enjoyed their own little economy the size of Morocco’s supported by subsidies from the UK taxpayer that could be better used fixing the housing crisis.”

Hilton said those who wanted to buy somewhere to live were at a disadvantage compared with buyers who could write off interest against tax. He added: “It’s time landlords started paying more of their fair share so first-time buyers could have a level playing field and the government could have the resources to build more social housing.”

The call came as the Labour MP Frank Field said there should be an immediate review of public spending on housing, to increase building and reduce the UK’s housing benefit bill. “Instead of building more homes, taxpayers’ money is used to push up housing asset prices,” Field said. He added that parliamentary answers and research from the House of Commons library showed that the present housing shortage would “reinforce a growing disaster”.

The library research showed that the housing benefit budget had risen in real terms by 220% since 1985, while investment in housebuilding had fallen by 41%.

In the post-war period the number of new homes peaked at 352,000 in 1968, while the number of new social homes reached its highest level of 207,730 in 1954. In 2013, 22,510 social homes were built, out of a total of 109,640 newbuilds.

Next year £304m will be required to administer housing benefit.

Commenting on the data, Field said: “A national housebuilding programme is not only desirable, it is essential. The bill footed by the taxpayer to top up the rent money is out of control, because landlords know they can charge what they like, while renters are left to wait patiently for years for a new home.”